What if the next "national traitor" uses his Top Secret clearance to use that data stream to his own financial benefit?

Who's to say this hasn't already happened? I wouldn't put it past the 'Gang of Eight'[1] to use the NSA as a means to maintain their seat in power by quashing opposition, especially since it's been widely reported that the thorough congressional oversight has as many holes as Swiss cheese.

[1] http://en.wikipedia.org/wiki/Gang_of_Eight_(intelligence)